Safety stand for trailer loading

ABSTRACT

A method for supporting the nose of an unfettered trailer disposed on a surface adjacent a loading bay, including the steps of 1) providing a supporting assembly movable along the surface relative to the nose of the trailer, and also movable between a stored, collapsed position wherein the supporting assembly does not interfere with movement of vehicles over the surface, and a raised, engaging position in which a portion of the supporting assembly is disposed vertically above the surface and engages and supports the nose of the trailer; 2) moving the supporting assembly along the surface and relative to the nose of the trailer with the supporting assembly in the stored position, 3) sensing the nose of the trailer with a sensor that is movable with the supporting assembly relative to the nose of the trailer, and 4) in response to the sensor sensing the nose of the trailer, automatically moving the supporting assembly from the stored position to the raised engaging position to support the nose of the trailer.

This application is a continuation of co-pending application Ser. No.08/591,013 filed Jan. 25, 1996.

FIELD OF INVENTION

This invention in the preferred embodiment relates to tractor trailersand specifically to trailers which have been decoupled from the tractorat a loading dock and which will be secured in a position by a safetylocking device which engages the kingpin normally engaged by thetractor.

BACKGROUND OF THE INVENTION

It is known in the trucking industry to decouple the tractor from thetrailer after the trailer is positioned at a loading dock. A kingpin isprovided adjacent the front bottom portion of the trailer whoseconstruction is well known in the art. Typically the tractor includes abiased coupling plate (fifth wheel) for latching engagement with thekingpin.

Further supports have been provided along the body of a trailer towardsthe front of a trailer which may be cranked down to engage the ground soas to enable the trailer to be disengaged from the tractor and whichsupport remains in engagement with the ground to keep the trailer fromtoppling over.

When the trailer is located at the dock if loaded in a conventionalmanner, for example by a fork truck, the fork truck may drive well pastthe cranked down supports and hence risk toppling the trailer. Jackstands therefore may be provided adjacent the front of the trailer.However these are manually operated stands which are positioned neareach edge of the front of the trailer before loading. Unless these jackstands engage the metal plate reinforcement surrounding the kingpin orengage the kingpin itself then there is the risk of the failure of thestand during loading and the nose diving of the trailer. For example ifthe jack stands engage the floor channel of the trailer, which channelsmay be corroded, or the wooden floor boards of the trailer, depending onthe load distribution an accident may occur.

It would therefore be advantageous to provide a more substantial andpreferably centrally disposed support for the trailer proximate thefront end thereof, which support would engage adjacent to the metalplate reinforcement surrounding the kingpin or engage the kingpinitself, which pin is normally engaged by the tractor, and therebyprevent the trailer from nose diving or alternatively tail diving (ifthe rear wheels of the trailer are positioned so as to provide aconsiderable overhang toward the rear of the trailer) during normalloading.

U.S. Pat. No. 5,165,265 provides in combination with a security locksupport legs for engaging the support surface adjacent the forward endof an associated trailer.

U.S. Pat. No. 4,014,517 describes one example of a stand for supportinga structure such as a mobile home above the ground. The stand includes aflat broad base for engaging the ground and a plurality of legsassembled to the base. The legs converge from the base to a support 22so that the support platform may be positioned in a firm supportiverelationship to the structure. Manual operation of a handle 33 providesfor the hydraulic jacking of the support 22 to engage a structuralmember of the mobile home or the like.

U.S. Pat. No. 4,169,579 provides a support assembly for supporting atongue of a trailer and adjustable to establish the tongue at a desiredelevation from the ground so as to enhance hitching to a towing vehicle.

Nowhere in the prior art is there provided a collapsible, (for examplefolding), safety stand for engagement in one position, for example tothe kingpin of an unfettered trailer or the like or that may bepositioned adjacent the kingpin of the trailer proximate the reinforcingplate provided with the kingpin to provide prevention of nose diving ofthe trailer during loading or unloading and which safety device may bealternatively positioned in a flat stored position to allow a tractoraccess for hitching the trailer.

It is therefore a primary object of the invention to provide acollapsible (for example folding), trailer safety stand which is locatedin the bay in which a trailer is normally docked.

It is a further object of the invention to provide a collapsible, (forexample folding), safety stand which has a portion which engagesadjacent to or to the kingpin of an unfettered trailer, which isnormally engaged by a tractor when locating the trailer in a dockedposition.

It is yet a further object of the invention to provide a collapsible,(for example folding), safety stand which has a moveable portion whichengages adjacent to, or to the kingpin of an unfettered trailer, whichis normally engaged by a tractor when locating the trailer in the dockedposition. The moveable portion may further accommodate various lengthsof trailers.

Further and other objects of the invention will become apparent to thoseskilled in the art when considering the following summary of theinvention and the more detailed description of the preferred embodimentsillustrated herein.

SUMMARY OF THE INVENTION

According to a primary aspect of the invention there is provided acollapsible trailer safety stand comprising a base locatable adjacentthe front of a loading bay a predetermined distance away from a dock soas to be located adjacent the kingpin of an unfettered trailer, thekingpin normally engaged by a tractor and the unfettered trailer beingpositioned in the loading bay adjacent to the dock when the trailer isdisconnected from the tractor, the collapsible safety stand having a topand bottom and having located, proximate its bottom the base havingpivotally attached thereto at least one lifting arm and at least onestabilizing arm, said arms having pivotally attached therewith asupport, and preferably a kingpin engaging mechanism, disposed proximatethe end of said arms remote the base and being moveable from a firstposition wherein the support is disposed substantially within the basewhereat the safety stand lays substantially flat in the loading bay soas not to interfere with the movement of a tractor trailer whendecoupling the trailer, to a second position wherein the support isdisposed adjacent the kingpin, (and preferably to a third positionwherein, when the support is a kingpin engaging mechanism, the supportlocks the trailer in a locked position, and in one embodiment whereatsaid arms are disposed at an angle greater than ninety degrees from thefirst position, and engages against the kingpin with a force sufficientto prevent the forward motion of the trailer, to lock the trailersubstantially in the dock of the loading bay when the trailer isdocked), the arms being engaged with a drive (preferably a hydrauliccylinder or a pneumatic cylinder or mechanical/electric drive) to drivesaid support from the first position to the second position locating themechanism adjacent to said kingpin of said tractor trailer, (andpreferably to said third locked position when the support engages thekingpin) whereby the collapsible safety stand prevents nose diving ofthe trailer when the trailer is being loaded or unloaded by conventionalmeans. For example, if a fork truck were to drive in an empty trailertoward the front thereof adjacent to the kingpin past the supportsprovided along the body of a trailer towards the front of a trailerwhich are cranked down to engage the ground, depending on the method ofloading of the trailer, there is a risk of overturning the trailer. Byusing the trailer safety stand such a problem is obviated, especiallywhen the support engages the kingpin since only slight lateral movementis possible.

In a preferred embodiment of the invention when the support engages thekingpin, the support has a generally V-shaped notch provided therewithto engage the kingpin in order to locate the kingpin as close to thenotch as possible when the support moves to the third position. TheV-shaped notch will provide, during movement from the second to thethird position, a constant force tending to center the kingpin of thetrailer in the support as the support pushes against the kingpin at thethird position. The trailer may therefore initially or duringprogressive stages of loading be moved laterally as a result of saidconstant force, regardless of the point of engagement of the generallyV-shaped notch with the kingpin, within the boundaries of the support.

In one embodiment the at least one stabilizing arm is offset toward theend of the support not having the generally V-shaped notch therein. Thesupport therefore having the generally V-shaped notch provides aprovision for exerting a constant force resulting in the shifting of atrailer toward the center line of the bay if the trailer was not alreadyproperly positioned by the tractor at that point. Further by preferablyhaving the support engage the kingpin, normally engaged by the tractor,in the second position, further movement of the support to the thirdposition may under the constant force exerted drive the trailer backtoward the dock if the trailer is empty or in the process of beingunloaded, wherein the third position becomes a locking positionpreventing forward movement of the trailer against the constant forceapplied by the safety stand.

According to yet another aspect of the invention there is provided acollapsible trailer safety stand to be located adjacent the kingpin ofan unfettered trailer the kingpin being surrounded by a mounting plateand normally engaged by the tractor of the vehicle, the collapsibletrailer safety stand comprising:

a stationary base having two ends and having at least one rail orchannel extend from proximate one end to proximate the other end,

a sled having sides, a top, and two ends and being moveable within saidbase from proximate one end to proximate the other end of said base,said sled having side members, the sled having rollers, wheels, orsliding bearing members extending laterally away from the side membersthereof in engagement with the at least one rail or channel of saidbase, the rollers/wheels/or sliding bearing members or the like beingprevented from leaving the at least one rail or channel by the sidemembers of the sled and the at least one rail or channel, therebyallowing the sled to be moveable along the base member from proximateone end to proximate the other end,

the base preferably including a multiplicity of stop positions for thesled between the ends of the base, for example to allow for variousunfettered trailer lengths,

the sled having pivotally attached thereto at least one lifting arm andat least one stabilizing arm, said arms having pivotally attachedtherewith a support, and preferably a kingpin engaging mechanism,disposed proximate the end of said arms remote said base and beingmoveable from a first position wherein the support is disposedsubstantially within the sled, whereat the support lays substantiallyflat in the sled so as not to interfere with the movement of a tractortrailer when decoupling the trailer, to a second position wherein thesupport is disposed adjacent the kingpin, (and preferably to a thirdposition wherein, when the support is a kingpin engaging mechanism, thesupport locks the trailer in a locked position, preferrably whereat saidarms are disposed at an angle greater than ninety degrees from the firstposition, and engages against the kingpin with a force sufficient toprevent the forward motion of the trailer to lock the trailersubstantially in the dock of the loading bay when the trailer isdocked), the arms being engaged with a drive (preferably a hydrauliccylinder or a pneumatic cylinder or a mechanical/electrical drive) todrive said support from the first position to the second positionlocating the support adjacent to said kingpin of said tractor trailer,(and preferably to said third position when the support locks thekingpin),

the sled being moveable within the base, when the support is in thefirst stored position, to and from proximate the trailer by a seconddrive preferably engaged with one of the rollers/wheels or slidebearings to locate the sled at one of the preferred multiplicity of stoppositions proximate the nose of the unfettered trailer for any sizetrailer so that the support is able to accurately move at least to thesecond position, the sled having a sensor in communication with thedrive to sense when the sled is adjacent the nose of the unfetteredtrailer to locate the sled at a position consistent with the length ofthe trailer such that when the support moves it will be in the correctsecond position and preferably be at the kingpin engaging position,

preferably the drive for the arms including means for locking the sledat the multiplicity of stop positions when the support is moved to thesecond position, preferably the drive being a hydraulic cylinder havinga tab extending from the pivot thereof remote the support which will notinterfere with the motion of the sled when the support is in the firstposition but which engages a predetermined portion of the base at eachof the multiplicity of stop positions when the support moves to thesecond position (preferably engaging a flat plate interconnecting thesides of the base proximate each stop position)

whereby the collapsible safety stand when in the second or preferredthird position prevents nose diving of the trailer when the trailer isbeing loaded by conventional means.

In one embodiment when the first drive is a hydraulic cylinder a hosereel is provided with the stationary base proximate the end of the baseremote the trailer which hose reel takes up and lets out hose as thesled moves toward or away from the unfettered trailer. In anotherembodiment when the second drive is a hydraulic motor, a cable reel isprovided with the stationary base proximate the end of the base remotethe trailer which cable reel takes up and lets out cable as the sledmoves toward or away from the unfettered trailer.

In a preferred embodiment of the invention when the support engages thekingpin, the support has a generally V-shaped notch provided therewithto engage the kingpin in order to locate the kingpin as close to thenotch as possible when the support moves to the third position. TheV-shaped notch will provide, during movement from the second to thethird position, a constant force tending to center the kingpin of thetrailer in the support as the support pushes against the kingpin to thethird position. The trailer may therefore be initially or duringprogressive stages of unloading moved laterally as a result of saidconstant force, regardless of the point of engagement of the generallyV-shaped notch with the kingpin, within the boundaries of the support.

In one embodiment the at least one stabilizing arm is offset toward theend of the support not having the generally V-shaped notch therein. Thesupport therefore having the generally V- shaped notch provides aprovision for exerting a constant force resulting in the shifting of atrailer toward the center line of the bay if the trailer was not alreadyproperly positioned by the tractor at that point. Further by preferablyhaving the support engage the kingpin, normally engaged by the tractor,in the second position further movement of the support to the thirdposition may under the constant force exerted drive the trailer backtoward the dock if the trailer is empty or in the process of beingunloaded, wherein the third position becomes a preferred lockingposition preventing forward movement of the trailer against the constantforce applied by the safety stand.

According to yet another aspect of the invention there is provided acollapsible machine comprising

a stationary base having two ends and having at least one rail orchannel extend from proximate one end to proximate the other end,

a sled having sides, a top, and two ends and being moveable within saidbase from proximate one end to proximate the other end of said base,said sled having side members, the sled having rollers, wheels, orsliding bearing members extending laterally away from the side membersthereof into engagement with the at least one rail or channel of saidbase, the rollers/wheels/or sliding bearing members or the like beingprevented from leaving the at least one rail or channel by the sidemembers of the sled and the at least one rail or channel, therebyallowing the sled to be moveable along the base member from proximateone end to proximate the other end.

the base preferably including a multiplicity of stop positions for thesled between the ends of the base,

the sled having pivotally attached thereto at least one lifting arm andat least one stabilizing arm, said arms having pivotally attachedtherewith a support disposed proximate the end of said arms remote saidbase and being moveable from a first position wherein the support isdisposed substantially within the sled, whereat the support layssubstantially flat in the sled, to a second position wherein the supportis disposed a vertical distance from the sled and the base, (andpreferably to a third position whereat said arms are disposed at anangle greater than ninety degrees from the first position when layingflat in the sled, the arms being engaged with a drive (preferably ahydraulic cylinder or a pneumatic cylinder or a mechanical/electricaldrive) to drive said support from the first position to the secondposition and preferably to said third position,

the sled being moveable within the base between the ends thereof, whenthe support is in the first stored position, to and from proximate apredetermined position by a second drive preferably engaged with one ofthe rollers/wheels or slide bearings to locate the sled at one of thepreferred multiplicity of stop positions so that the support is able toaccurately move at least to the second position, the sled having asensor in communication with the drive to sense when the sled isadjacent the predetermined position to locate the sled thereat such thatwhen the support moves it will be in the correct second position,

preferably the drive for the arms including means for locking the sledat the multiplicity of stop positions when the support is moved to thesecond position, preferably the drive being a hydraulic cylinder havinga tab or clip extending from the pivot thereof remote the support whichwill not interfere with the motion of the sled when the support is inthe first position but which engages a predetermined portion of the baseat each of the multiplicity of stop positions when the support moves tothe second position (preferably engaging a flat plate interconnectingthe sides of the base proximate each stop position)

whereby the machine when in the second or preferred third position maybe used as a safety stand.

In one embodiment when the first drive is a hydraulic cylinder a hosereel is provided with the stationary base proximate the end of the basewhich hose reel takes up and lets out hose as the sled moves between theends of the base. In another embodiment when the second drive is ahydraulic motor a cable reel is provided with the stationary baseproximate the end of the base which cable reel takes up and lets outcable as the sled moves between the ends of the base.

According to yet another aspect of the invention there is provided acollapsible machine comprising a top and bottom and having locatedproximate its bottom a base having pivotally attached thereto at leastone lifting arm and at least one stabilizing arm, said arms havingpivotally attached therewith a support disposed proximate the end ofsaid arms remote said base and being moveable from a first positionwherein the support is disposed substantially within the base whereatthe mechanism lays substantially flat, to a second position wherein thesupport is disposed a vertical distance from the base, (and preferablyto a third position whereat said arms are disposed at an angle greaterthan ninety degrees from the first position when laying flat in thebase, the arms being engaged with a drive (preferably a hydrauliccylinder or a pneumatic cylinder) to drive said support from the firstposition to the second position and preferably to said third positionwhereby the machine when in the second or preferred third position maybe used as a safety stand.

In a preferred embodiment of the inventions described in the aboveparagraphs the at least one stabilizing arm and the at least one liftingarm cooperate to maintain the support substantially horizontal at alltimes whether in the first, second, or third positions or movingtherebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side plan view of the support illustrated in its collapsed,first position, and illustrated in a preferred embodiment of theinvention.

FIG. 1A is a schematic view of the support of FIG. 1 illustrated in aloading bay occupied by a trailer and illustrated in a preferredembodiment of the invention.

FIG. 2 is a side elevation view of the support of FIG. 1 shown in asecond preferred position prior to engaging the pin of a trailer andillustrated in the preferred embodiment of the invention.

FIG. 3 is a schematic view of the support when engaging the pin of thetrailer illustrated in an alternative embodiment of the invention toFIG. 2.

FIG. 4 is a view similar to FIGS. 2 and 3 illustrating the final orthird position of the support illustrated in a preferred embodiment ofthe invention.

FIG. 5 is a top plan view of the invention illustrating a centeringfeature of the support and illustrated in a preferred embodiment of theinvention.

FIG. 6 is a side schematic view of a preferred embodiment of theinvention similar to that described in relation to FIGS. 1 through 5with the exception that the base includes therewith a moveable sledwhich houses the kingpin support, illustrated in a preferred embodimentof the invention.

FIG. 7 is a top schematic view of the base 105 of FIG. 6 illustrated ina preferred embodiment of the invention.

FIG. 8 is a top schematic view of the sled of FIG. 6 illustrated in apreferred embodiment of the invention.

FIG. 9 is a top perspective view of the entire mechanism of FIG. 6illustrated in a preferred embodiment of the invention.

FIG. 9A is a side view of FIG. 9.

FIG. 9B is an end view of FIG. 9.

FIG. 10 is a perspective view of the sled of FIG. 8 illustrated in araised position in a preferred embodiment of the invention.

FIG. 11 is an exploded perspective view of the mechanism illustrated inFIGS. 6 through 10 and illustrated in a preferred embodiment of theinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring generally to FIGS. 1 through 5 there is illustrated acollapsible supporting device 10 located in loading bay B as shown inFIG. 1 and FIG. 1A. The trailer is supported upon a surface S onsupports W after the tractor has disengaged therefrom. The collapsiblesupporting device 10 is located on the surface S and is moveable from afirst collapsed position substantially shown in FIGS. 1 and 1A to araised position shown in FIG. 2 and 3 and finally to a locked positionas shown in FIG. 4. In one embodiment the collapsible safety supportstand may be anchored to the ground via plates 5 and 45. The plate 5 haspivotally attached thereto at pivot 20A lifting arms 20. A stabilizingarm 21 is pivotally attached to the plate 5 at pivot 21A. A supportplate 30 substantially as seen in FIG. 5 is provided for engagement withthe kingpin P normally engaged by the tractor. The plate 30 is pivotallyattached to the two lifting arms 20 at pivots 20B and to the supportingarm 21 at pivot 21B. The two lifting arms and the stabilizing arm 20 and21 respectively are aligned substantially parallel to one another duringthe phases of motion of the supporting device. A hydraulic cylinder 40pivotally attached at 40A to a base 45 is provided for moving the arm 20to and from the initial collapsed position seen in FIG. 1 to the finalraised position best seen in FIG. 4. The rod 41 is attached to a piston47 which is moved by hydraulic fluid in conventional manner. Theextension therefore of the cylinder from its first collapsed position ofFIG. 1 wherein the arm is substantially flat to a raised position asseen in FIG. 2 wherein the lifting arm and a stabilizing arm aresubstantially at an angle less than 90 degrees in relation to the base5. The piston rod 41 is attached to one of the arms 20 at a pivot 40B.The pivot 40B passes through a link 6. The pivot 40B is locatedproximate the narrow end of link 6 and a torque tube passes between bothlifting arms 20 to interlock the two arms and to ensure that the motionof the cylinders is passed to both arms. The platform 30 is attachedproximate the top of the lifting and stabilizing arm 21 and engages thekingpin P as best seen in FIG. 4 preferrably at an angle greater than 90degrees to the base 5. (It may engage the kingpin at any angle witheffective results.) In this position, the plate 30 pushes against thekingpin P as best seen in FIG. 5 so that the kingpin P may substantiallymove toward a centered position within the notch 35, plate 30 therebymoving the trailer T to a substantially centered position within thebay. The trailer therefore may be pressed substantially against the dockby the motion of the support of the collapsible safety stand to thepreferred third position of FIG. 4 thereby providing a constant forceagainst the trailer and locking the trailer from moving away from thedock since it cannot move forward against the constant force of thecylinder 40. (Throughout this disclosure the meaning of locked isdefined in this manner.)

The trailer is then ready to safely load without the risk of turningover the trailer in a direction D should the safety support stand not bepresent.

Referring specifically to FIGS. 6 through 11, there is illustratedanother preferred embodiment of the invention. The advantage of FIGS. 6through 11 over the previously described embodiment is that the designof the safety stand will accommodate various lengths of trailers. Forexample, it is well known that trailers have various lengths of 40',45', 48' and 53'. The present embodiment endeavours to provide amechanism which will, when installed in a loading bay, compensate forthe length of the trailer being preferrably locked in position.

FIG. 6 specifically refers to a trailer T which has been positioned anduncoupled from its tractor in a loading bay on a surface. In thisregard, please refer to FIG. 1A. However, in this embodiment, thetrailer may not be a fixed length, and therefore the base 105 mustprovide for a certain amount of flexibility in positioning the support130 in relation to the kingpin P of the trailer. The kingpin typicallyhas a supporting plate surrounding it to provide secure anchoring of thekingpin into the trailer. Such structures are well known in the art, andthe reader is referred to those structures for further information inrelation to the kingpin. Typically, a trailer is best engaged at thekingpin by my safety stand. Alternatively, my safety stand could bepositioned adjacent a kingpin, but in doing so would not provide thelocking feature, but would prevent severe nose diving of the trailer.

Referring therefore to FIGS. 6 through 11, there is provided a base 105which is set in position in a loading bay parallel to the loading bay.As best seen in FIG. 9A and B, the base 105 has a low profile which maybe traversed by the wheels of a tractor when positioning the trailer.Therefore, it is highly recommended that the base 105 be structured ofsubstantial material sufficiently rugged to withstand the pounding thatthe trucking industry would impart upon such a device. All components ofthis system are recommended to be of such a structure. The base containsa front end 105A and a rear end 105B. The front end 105A of the base 105includes a notch 106 wherein a hose reel R1 and cable reel R2 lets outand takes up hydraulic hose H and electric cable E as best seen inrelation to FIG. 11. The hose reels R1 and R2 therefore lets out andtakes up hydraulic hose H and electric cable E to feed the cylinders 140and drive M in a conventional manner. The base 105 has located along thelength thereof reinforcing members 253, 248, 245 and 240 correspondingto the length of the trailer being docked in position. As best seen inFIG. 11, these flat bar elements are affixed by fasteners F1 atrespective openings O1 within the side channels C1 of the base 105. Theside channels C1 and C2 are provided for the purpose of allowing thesled 110 to move forward and reverse in the channels C1 and C2. As bestseen in relation to FIG. 10, rollers R are disposed on each side of thesled 110 and said rollers are contained within the channels C1 and C2.Therefore, in use the rollers cannot jump off of the rails C1 and C2.The sled 110 as best seen in FIGS. 8 and 10 will move in the base 105until such time as the correct position for the respective trailer beinglocked is achieved. This position is determined by a sensor 150 providedadjacent one end of the sled 110, adjacent the support 130. This sensormay be a sonar device to sense when the nose of the trailer has beenreached so that the sensor may be positioned substantially in line withthe kingpin to enable the support 130 to move from its collapsedposition to the locking position substantially shown in FIG. 6. Thesensor 150 may be located intermediate the two cylinders 140 affixed toa flat bar 116 (as best seen in FIG. 10) positioned to sense the nose ofthe trailer and thereby position the safety stand for each respectivetrailer length.

Provided near the ends of the pivots for the cylinders 140 areengagement portions which engage in front of each of the respective flatbar portions 240, 245, 248 or 253 when the safety stand is raised to itslocking position. Normally, the detent of the pivot is retained on theflat bar prior to the cylinders extending. As they extend in an upwardmotion, the detent of the pivot will tend to rest in the position shownin detail A of FIG. 11. This feature therefore provides locking of thesafety stand in that particular position using a simple detent of apivot which is rotated downwardly abutting the front of the flat bar asdescribed above. This works in conjunction with the forward motion ofthe support plate 130 from a collapsed position contained within thesled to a second position adjacent the kingpin and to a kingpin engagingposition (a third preferred locking position) wherein the kingpin isengaged by the substantially V-shaped portion of the support as bestseen in relation to FIG. 10. A surface 131 therefore will engage thekingpin P and tend to center the kingpin toward the bottom of the V at132. When a constant force is applied against the kingpin tending tocenter the kingpin in relation to the support 130, then a trailer maymove laterally. Once locked in position by the forward motion of thecylinder 140 and the lifting arms 120 and stabilizing arms 121 incombination with the detent of the pivot of the cylinder 140 engagingthe flat bar portion, then it can be readily seen that the safety standdoes provide excellent locking benefits.

The lifting arms as best seen in FIG. 8, 10 and 11 are pivoted to theframe portion 155 of the sled 110 at pivots 120A and 121A respectivelyand proximate the support 130 at 120B and 121B. It is noted that thepositioning of the pivots for the arm 121 are to the rear and to thelateral edges of the support plate 130 with respect to the pivots of thelifting arm 120 to keep the support horizontal at all times. The liftingarm 120 is engaged with a frame portion 147 which are engaged in turn bythe rods 141 of the cylinders 140 to provide a firm braced supportingstructure which will move coincidentally.

As best seen in FIG. 10, the sled therefore is provided with a hydraulicmotor assembly M which drives the powered roller R1 which drives thesled within the channels C1, C2 of base 105.

The operation of the sled in the base is therefore consistent with thedescription in relation to FIGS. 1 through 5 in that the support willmove firstly with the sled to be positioned for the respective trailerbeing unloaded, for example a 53' trailer, and will once positioned bepowered to raise from the collapsed position to a second positionsimilarly as illustrated in FIG. 2 and to a locked position, a positionsimilar to that which is illustrated in FIG. 4. At this position, aconstant pressure is exerted against the kingpin P by cylinders 140.This constant pressure will tend to center the trailer as it is beingunloaded.

Therefore, once a tractor positions a trailer in a loading bay, thedriver will winch down the supports W to the supporting surface S andsubsequently disconnect the trailer. The base 105 therefore ispositioned in the loading bay and in a plurality of loading baysrepetitively as is required by the depot being serviced. Once the driverleaves with the tractor, the safety stand is positioned in its lockedposition by an operator. The operator commences the initiation of theunit or this may be done automatically in a conventional manner. Oncethe sled moves in the base to the respective position for the particulartrailer that has been positioned in the loading bay, the sled will stopand then move from its first collapsed position to a secondsubstantially vertical position to a third substantially locked positionwherein the kingpin is engaged by the V-shaped engaging surface 131 ofthe support 130. The cylinders therefore provide a constant force topush back against the kingpin and prevent the trailer from nose divingor alternatively tail diving depending on the structure of the trailer.The present invention therefore provides a safety stand that iscollapsible and also which locks the trailer in position and provides asupport adjacent a kingpin and a locking effort against the kingpin forthe trailer regardless of the length of the trailer.

The sensor 150 which may be any reliable sensor such as sonar, infrared,or other known sensors, also includes the necessary electronics to startand stop the hydraulic motor M to position the sled in the base. Thedetails of such a sensor and control system are of conventionalstructures and are therefore not described.

Alternatively, a fifth wheel may be used as the support structure withequal success, adding the ability to latch the kingpin. Further, a latchmechanism can be added to the kingpin engaging mechanism shown in theFigures with equal latching results.

As many changes can be made to the preferred embodiments of theinvention without departing from the scope thereof; it is consideredthat all material contained herein be considered illustrative of theinvention and not in a limiting sense.

What is claimed is:
 1. A method for supporting the nose of an unfetteredtrailer disposed on a surface adjacent a loading bay, comprising thesteps of:providing a supporting assembly movable along the surfacerelative to the nose of the trailer, and also movable between a stored,collapsed position wherein the supporting assembly does not interferewith movement of vehicles over the surface, and a raised, engagingposition in which a portion of the supporting assembly is disposedvertically above the surface and engages and supports the nose of thetrailer; moving the supporting assembly along the surface and relativeto the nose of the trailer with the supporting assembly in the storedposition; sensing the nose of the trailer with a sensor that is movablewith the supporting assembly relative to the nose of the trailer; inresponse to the sensor sensing the nose of the trailer, automaticallymoving the supporting assembly from the stored position to the raisedengaging position to support the nose of the trailer.
 2. The method ofclaim 1, and including the further step of locking the supportingassembly in position on the surface, to prevent the supporting assemblyfront moving over the surface while in the raised, engaging position.